- Drugs that potently inhibit cytochrome P450 family 3, subfamily A, polypeptide 4 (CYP3A4) should be prohibited or used with caution; drugs which are strong inducers of CYP3A and may result in lower exposures of GSK2141795 should also be prohibited; drugs that are substrates of CYP3A4 or cytochrome P450 family 2, subfamily C, polypeptide 8 (CYP2C8) with a narrow therapeutic index may be prohibited; drugs that are sensitive substrates of CYP3A4 or CYP2C8 should be used with caution